The IEEE 802.16 working group has recently defined a Point-to-Multipoint (hereinafter, “P-MP”) communication method by which a plurality of MSs can be connected to BS.
Moreover, the IEEE 802.16 working group has defined two kinds of applications of the 802.16d specification (802.16-2004) for fixed communication and the 802.16e specification (802.16e-2005) for mobile communication.
A wireless communication system that employs the IEEE 802.16d/e mainly employs an orthogonal frequency division multiplex (OFDM) system and an orthogonal frequency division multiplexing access (OFDMA) system.
FIG. 14 is a block diagram illustrating the schematic configuration of a wireless communication system 100 that employs IEEE 802.16d/e.
The wireless communication system 100 illustrated in FIG. 14 includes Internet 101, an access service network (hereinafter, “ASN”) 104 that accommodates and connects a plurality of macro BSs 103A of which each wirelessly accommodates a plurality of MSs 102, and a connectivity service network (hereinafter, “CSN”) 105 that connects the Internet 101 and the ASN 104 for communication.
The ASN 104 further includes an ASN gateway (hereinafter, “ASN-GW”) 106 that takes charge of a communication interface between the CSN 105 and the ASN 104 and that transfers packets in Layer 2, in addition to the plurality of macro BSs 103A. Moreover, the CSN 105 routes packets and transfers the packets in Layer 3.
A femto BS that is made by downsizing the macro BS 103A is being recently developed. In this way, there is devised a technology for placing a femto BS in a standard home or an office that has a bad radio wave environment and connecting the femto BS and the ASN 104 by way of an Internet service provider (hereinafter, “ISP”) and the Internet 101.
FIG. 15 is a block diagram illustrating the schematic configuration of a wireless communication system 100A that uses a femto BS. The same configuration as that of the wireless communication system 100 illustrated in FIG. 14 has the same reference numbers, and thus the explanation of the same configuration and operation is omitted.
The wireless communication system 100A illustrated in FIG. 15 includes a femto BS 103B that is placed in, for example a standard home or an office and wirelessly accommodates the MS 102.
The femto BS 103B is connected to an ISP 108 through an asymmetric digital subscriber line (hereinafter, “ADSL line”) and an optical fiber line, and is connected to the ASN 104 for communication directly or by way of the Internet 101 from the ISP 108.
Moreover, the ASN 104 includes a femto GW 109 that takes charge of a communication interface with the femto BS 103B by way of the ISP 108 and/or the Internet 101.
The femto GW 109 uses an IP security (hereinafter, “IPsec”) to realize an encryption communication with the femto BS 103B for preventing eavesdropping and interpolation of data and to assure the security of the ASN 104.
FIG. 16 is a block diagram illustrating the schematic configuration of a wireless communication system 100B that uses the femto BSs 103B. The same configuration of the wireless communication system 100B as that of the wireless communication system 100A illustrated in FIG. 15 has the same reference numbers, and thus the explanation of the same configuration and operation is omitted.
The wireless communication system 100B illustrated in FIG. 16 provides the plurality of macro BSs 103A and the plurality of femto BSs 103B, which have geographically adjacent relationship, in the same paging group (hereinafter, “PG”). For convenience of explanation, the macro BS 103A and the femto BS 103B is generally named as a BS 103.
When a packet heading to the MS 102 wirelessly accommodated in the BS 103 in the same PG is received, the ASN-GW 106 instructs all the macro BSs 103A and all the femto BSs 103B in the same PG to transmit paging information of the MS 102.
Moreover, the MS 102 enables to set an idle mode. During the idle mode, a power consumption can be reduced because signals output from the macro BS 103A or the femto BS 103B need not be constantly received.
The ASN-GW 106 further includes a paging controller (hereinafter, “PC”) unit that registers PG in which the MS 102 during an idle mode is located.
When a movement, which is a PG change, from the current-position PG to the BS 103 belonging to another PG is detected, the MS 102 requests the ASN-GW 106 to perform location registration in order to request to register new position information in a location registration database.
Because the BS 103 periodically sends its PGID to the underneath MS 102, the MS 102 detects a PG change caused by the movement of the MS 102 in accordance with the PGID output from the BS 103.
When the location registration request of the MS 102 is detected, the PC unit of the ASN-GW 106 registers new position information in the location registration database as the latest position information of the MS 102. Moreover, the location registration request of the MS 102 starts in accordance with the time-up of a timer (idle mode timer) that is managed by the MS 102, in addition to the case where the PG change caused by the movement of the MS 102 is detected.
Moreover, when a packet for the MS 102 during an idle mode is received, the ASN-GW 106 specifies the MS 102 from header information of the received packet and sends paging public information including a paging parameter and an identifier of identifying the specified MS 102 to all the BSs 103 in the PG in which the MS 102 is located.
Upon receiving the paging public information from the ASN-GW 106, each the BS 103 transmits paging information to the underneath MS 102.
FIG. 17 is an operating sequence diagram illustrating processing operations of the wireless communication system 100B that are associated with a basic location registration updating process.
When a starting timing of the location registration updating process is detected (Step S201), the MS 102 illustrated in FIG. 17 starts the location registration updating process. In this case, the starting timing starts, for example, in accordance with the detection of a PG change caused by the movement of the MS 102 or the time-up of the idle mode timer of the MS 102.
Upon detecting the starting timing, the MS 102 transmits a ranging request (hereinafter, “RNG-REQ”) to the BS 103 (Step S202). In this case, RNG-REQ is a message that includes a location registration request flag (hereinafter, “LU request flag”) of requesting the location registration updating process and a PCID of identifying the PC unit of the ASN-GW 106 associated with the MS 102.
Upon receiving the RNG-REQ, the BS 103 transmits a location registration request (hereinafter, “LU-Req”) to the ASN-GW 106 that includes the PC unit associated with the PCID of the RNG-REQ (Step S203).
Upon receiving the LU-Req, the ASN-GW 106 updates and registers the present PGID of identifying the present PG in which the MS 102 is located, the last BSID of identifying the BS 103 that performs the final location registration, parameters, and the like in the location registration database (Step S204). Simultaneously, the ASN-GW 106 resets a clocking operation of a system-side idle mode timer that monitors the starting timing of the location registration updating process in the ASN-GW 106 side. In this case, the system-side idle mode timer performs time-up in a little longer time than that of the idle mode timer that is managed by the MS 102.
Furthermore, the ASN-GW 106 sends back a location registration request response (hereinafter, “LU-Rsp”) for the LU-Req output from the BS 103 to the BS 103 (Step S205). In this case, LU-Rsp includes key information for calculating a cipher-based message authentication code (hereinafter, “CMAC) for authenticating RNG-REQ in the BS 103 side.
Upon receiving the LU-Rsp output from the ASN-GW 106, the BS 103 confirms the validity of RNG-REQ by authenticating CMAC on the basis of the key information of the LU-Rsp. When the validity is confirmed, the BS 103 transmits a ranging request response (hereinafter, “RNG-RSP”), which includes a flag indicating a location registration success and the present PGID, to the MS 102 (Step S206).
Furthermore, after the RNG-RSP is transmitted to the MS 102, the BS 103 sends back a location registration request confirmation (hereinafter, “LU-Confirm”) to the PC unit of the ASN-GW 106 (Step S207).
On the other hand, when the validity of RNG-REQ cannot be confirmed at Step S206, the BS 103 transmits the RNG-RSP including a flag indicative of a location registration failure to the MS 102, and then sends back the LU-Confirm to the PC of the ASN-GW 106. Then, the ASN-GW 106 cancels the updating for location registration.
FIG. 18 is an operating sequence diagram illustrating processing operations of the wireless communication system 100B associated with a basic paging process.
Upon receiving the packet for the MS 102 during an idle mode (Step S211), the PC unit of the ASN-GW 106 illustrated in FIG. 18 transmits paging public information that includes a start code indicating a transmission start of paging information for the MS 102 to all the BSs 103 in the PG of the present PGID reported by the MS 102 at the location registration updating process (Step S212).
Upon receiving the paging public information including the start code, each the BS 103 transmits paging information (PAG-ADV) to the MS 102 that is a paging target (Step S213). Moreover, the paging public information and the paging information (PAG-ADV) include a MAC address, a hash value, and the like for specifying the MS 102 that is a paging target.
Moreover, until the paging public information including a stop code to be described below is received, the time-up of a paging public information timer included in the paging public information is performed, or the response to RNG-REQ is received from the MS 102, each the BS 103 continues to transmit the paging information (PAG-ADV) with a predetermined paging period.
Upon receiving the paging information including its own MAC address (or hash value), the MS 102 transmits to the BS 103 a reconnection request flag for terminating the idle mode and requesting network reconnection and RNG-REQ including the PCID of identifying the PC unit of the ASN-GW 106 associated with the MS 102 (Step S214).
Upon receiving the RNG-REQ, the BS 103 determines that the paging-target MS 102 exists thereunder, and transmits an idle mode exit request of requesting network reconnection to the PC unit of the ASN-GW 106 by terminating the idle mode by the MS 102 on the basis of the PCID of the RNG-REQ (Step S215).
Upon receiving the idle mode exit request, the PC unit of the ASN-GW 106 sends back to the BS 103 an idle mode exit response including registration information of the paging-target MS 102 in addition to key information for calculating CMAC that is used for authenticating RNG-REQ (Step S216).
Upon receiving the idle mode exit response, the BS 103 authenticates CMAC on the basis of the key information of the idle mode exit response to confirm the validity of RNG-REQ. When the validity is confirmed, the BS 103 transmits to the MS 102 RNG-RSP including optimization information such as communication-start connection information in addition to a location registration updating success (Step S217), and starts communication with the MS 102.
Furthermore, the ASN-GW 106 transmits paging public information including a stop code to all the BSs 103 in the same PG (Step S218). Upon receiving the paging public information including the stop code, the BS 103 stops the continuous transmission of the paging information.
However, because the femto BS 103B and the femto GW 109 are connected by a point to point encryption tunnel such as an IP security in the wireless communication system 100B including the femto BS 103B, paging information cannot be delivered in a multicasting manner, and thus it is required to suppress the number of deliveries of paging information to the minimum.
In other words, when the femto BSs 103B of which the number is, for example, 1000 exist thereunder, the femto GW 109 should copy paging information for the underneath MS 102 1000 times and transmit the paging information to all the femto BSs 103B. This leads to consume a large bandwidth on the Internet 101 in addition to the process burden.
FIG. 19 is an explanation diagram plainly illustrating a normal paging function associated with each the BS 103 in the same PG.
When the BSs 103 “#1”, “#2”, and “#3” are in the same PG in the case of a normal paging function illustrated in FIG. 19, there is illustrated an example in which the MS 102 “#3” is under the BS 103 “#1” and the MS 102 “#1” is under the BS 103 “#2”, and the MS 102 “#2” moves by a route of the BS 103 “#1”->the BS 103 “#2”->the BS 103 “#3”.
In this case, when packets of the MSs 102 “#1”, “#2”, and “#3” are generated, all the BSs 103 “#1”, “#2”, and “#3” in the same PG transmit the paging information of the MSs 102 “#1”, “#2”, and “#3”.
However, in the case of the normal paging function, each the BS 103 in the same PG should deliver the paging information of the paging-target MS 102 regardless of the case where the MS 102 does not exist under the BS 103. For example, because the BS 103 “#2” transmits the paging information of the MS 102 “#3” in addition to the paging information of the MSs 102 “#1” and “#2” regardless of the case where the MSs 102 “#1” and “#2” exist and the MS 102 “#3” does not exist in the BS 103 “#2”, the transmission of useless paging information occurs.
Therefore, a location based paging function for delivering the paging information of the paging-target MS 102 from only the BS 103 in which the MS 102 exists is considered in order to deal with such a situation.
FIG. 20 is an explanation diagram plainly illustrating a location based paging function associated with each the BS 103 in the same PG.
Assuming that the BS 103 and the MS 102 are arranged in the location based paging function illustrated in FIG. 20 similarly to the group configuration of the normal paging function illustrated in FIG. 19, each the BS 103 transmits the paging information of the MS 102 when the MS 102 exists under the BS 103 even in the case of the same PG. For example, when the MSs 102 “#1” and “#2” exist under the BS 103 “#2”, the BS 103 “#2” transmits only the paging information of the MSs 102 “#1” and “#2”. In this way, a data delivery amount of paging information can be reduced by preventing the delivery of useless paging information.
Non-Patent Document 1: IEEE Std 802.16 TM-2004
Non-Patent Document 2: IEEE Std 802.16e TM-2005
Non-Patent Document 3: IEEE 802.16m-08/579